USRSA Racquet Professional Study Guide - Racquet Technology PDF

RACQUET PROFESSIONAL STUDY GUIDE SECTION ONE RACQUET TECHNOLOGY UNDERSTANDING RACQUETS & STRING USRSA Racquet Professional Study Guide – Racquet Technology THE FRAME A frame is simply an unstrung racquet. A frame becomes a racquet once it is strung. The current frames available today are made of...

RACQUET PROFESSIONAL STUDY GUIDE SECTION ONE RACQUET TECHNOLOGY UNDERSTANDING RACQUETS & STRING USRSA Racquet Professional Study Guide – Racquet Technology THE FRAME A frame is simply an unstrung racquet. A frame becomes a racquet once it is strung. The current frames available today are made of high modulus graphite fibers, also called carbon fiber. Over the years, other materials have been used beginning with wood frames and later metal (either steel or aluminum). Aluminum is still being used for inexpensive racquets sold in chain stores, as well as some children's racquets. Since the mid 1980's composite frames have dominated the market. Many materials have been used including fiberglass, ceramic, titanium, boron and many other materials, but the core ingredient has been, and is, carbon fiber or high-modulus graphite. Most frames also have a plastic grommet and bumper guard system, along with a grip on the handle made of leather or a synthetic leather-like material. THE STRING Like frames, strings used in racquets have evolved through the years. Until the 1940's natural gut was the primary material used. Natural gut is made from the intestines of cattle or sheep, but never cats. The term "cat gut" was often used, but no one seems to know why. The most accepted theory is that the whining sound made when pulling the cross strings through the main strings during the stringing process mimicked a cat. During the 1950's, nylon string was made available as a cheaper alternative. Purists were slow to change but through the years the quality of both the material and construction improved, and by the 1980's, nylon string was the dominant material in the marketplace. Today, string materials and construction vary widely. There are more than 1,000 different string models currently on the market as manufacturers attempt to produce a product to meet the needs of every type of player. THE RACQUET The sum of the frame and the string becomes a Racquet. While over the years manufacturers continue to innovate, the basic racquet remains consistent. The head shapes may vary in size and shape along with other minor aspects, but the basic racquet shown is typical. Figure 1: Anatomy of a racquet Note: Stringers often refer to positions around a racquet's head in the same manner as a clock face, 12 o'clock being straight up, 1 o'clock the adjacent right shoulder, 6 o'clock straight down, and so forth. Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 1 USRSA Racquet Professional Study Guide – Racquet Technology CUSTOMER SERVICE Providing good customer service involves many facets, but we are going to concentrate on helping customers get the optimum performance from their racquet. That means having a racquet that meets their particular needs to begin with: 1.) All the attributes such as weight, balance, swing weight are working to give them the best performance possible. 2.) The grip size is correctly fitted. 3.) The string is the best for their frame and their style of play, and is installed at the correct tension to provide optimum performance. It also means being able to inspect their racquet and advise them on the condition and quality to meet their needs. This will require a dialogue with the customer to find out about their game, their expectations and any particular needs or requests they may have. Once you have the needed information, you will be able to use your knowledge of racquets to advise them on the best course of action regarding their racquet choice, as well as stringing and gripping of their racquet to keep it in peak performance condition. RACQUET PURCHASE Ideally you will want to help your customer choose a frame that fits their style of play and their swing type. As you learn about all the characteristics that contribute to the various attributes of the racquet, you will be better equipped to know how to follow up with more questions. But, for now we want to emphasize the need for you to gain as much information about the customer and their style of play as possible. The more information you have, the better equipped you will be to help them choose the right racquet. Client Questions We couldn't possibly list all the questions you need to ask here as each case will be different and the next question will be dependent upon the answer of the last question. The more you know about your client's game, the better you will be equipped to give them your best advice. These are just general ideas of the information you will need to give the best advice possible. Sample questions are in no particular order. 1. 2. 3. 4. 5. 6. 7. 8. How often do you play? Do you play singles, doubles or both? What level player are you? Beginner? Intermediate? Advanced? Do you have an NTRP Rating? How would you describe your style of play? Baseliner? Serve-Volley? All-Court? What is your current racquet? What do you like and/or dislike about it? Why are you looking for a new racquet? Have you experienced any injuries related to your game? Tennis Elbow? Shoulder or wrist? Would you say you try to win points by overpowering your opponents? Or are you more about moving the ball around and hitting a variety of shots? 9. Do you take a long, fast swing or is it more compact and slow? In order to utilize the knowledge gained from your client, you will have to understand the frame, the string and how those can fit together with your client to meet their needs. To do that we have broken things down, beginning with the frame. FRAME CATEGORIES Frames are generally divided into three groups based on the swing type of the player. These are general and there are always exceptions to the rules that can be determined as you assist the customer through the process. There is also a lot of variety within each category, but using the general breakdown is a good place to start. Game Improvement Frames: This category encompasses the most powerful frames, meaning they will generate more power and depth of shot with less effort than others. These frames usually have large heads, are lightweight, are very stiff and are generally designed for players with slower compact strokes. This Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement 2 and presentation of data are fully protected by copyright and may not be reproduced. USRSA Racquet Professional Study Guide – Racquet Technology category is also usually the most expensive since they are generally where the manufacturers tend to introduce new technology into the marketplace. Keep in mind that "Game Improvement" is just a label. While most beginners will experience benefit from these frames, it is not uncommon for highly skilled players to prefer them also. It is more about swing speed and stlye of play than it is about skill level. Player Frames: This category is the opposite end of the spectrum and includes the heavier frames with smaller heads. These racquets are designed for more advanced players with long, fast strokes. These players generate power with their strokes and need these less-powerful frames to help control the ball. Most of the touring professionals use racquets in this category. These frames tend to be less expensive since this player isn't interested in newer technology but rather in a solid frame that they are used to using. These players usually need several frames since they play tournaments and are more likely to be string-breakers. Intermediate Frames: This category combines a balance of the other two categories and frames in this category are often referred to as "tweeners" because they fall somewhere in the middle -- less powerful than the Game Improvement frames but more powerful than the Player Frames. This doesn't mean that this is the best balance for everyone, just that it fits the player with intermediate strokes. However, this is the most popular category as far as sales go, meaning more racquets in this category are offered and sold by manufacturers. Like most things, there are needs on either extreme but the mass falls somewhere in between. There is also a lot of variety within this category as some will trend closer to being like the Game Improvement frames and others will trend closer to being more similar to the Player Frames. PLAYER TYPES Short/Slow Swings: Players with slower, more compact swings tend to prefer Game Improvement frames simply because they get more depth and pace on their shots with less energy. In essence, they aren't generating much power with their strokes and they need more power from the racquet. Fast/Full Swings: Players with fast, long swings tend to prefer Player frames. These players are generating plenty of power on their own and need the racquet that will provide the least amount of power allowing them to control their shots. Moderate/Medium Swings: Players with moderate strokes, not too fast or too slow, tend to prefer Intermediate frames. Because of their swings, player frames tend to not generate enough depth or pace, while Game Improvement frames provide too much, making it difficult to keep the ball in play. To help your client make the best selection, you will want to find out what racquet or racquets they are using now or in the recent past. What did they like or dislike about them? Knowing this will give you a good base. Do they take a full, long, fast stroke at the ball or are their strokes slower and more compact? Do they try to impart spin on the ball? Do they try to overpower their opponents or are they more concerned with good ball placement? Do they play a baseline, serve and volley, or an all-court game? Do they break strings often? What type court surface do they usually play on? All these questions will provide information needed to make good suggestions for racquets for the customer to try. FRAME CHARACTERISITICS Matching certain player types together with their corresponding racquet category is just the most basic element of personalizing a player's frame selection. In order to help players find the right frame within their category, you first have to understand what they feel when using the racquet. We have identified four characteristics that most players can feel, and the following will explain how frames are made differently to enhance those characteristics in specific ways. It is important to remember that the speed and length of the players’ stokes contribute greatly to this. However, here we are specifically speaking of the frame only and consider all other factors to be equal. Power: This characteristic simply means how much energy is returned to the ball. In other words, the more powerful the racquet, the deeper and faster the ball will go when struck. Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 3 USRSA Racquet Professional Study Guide – Racquet Technology Maneuverability: This characteristic simply refers to how easy the racquet is to move or swing. Obviously, a heavier frame is harder to swing at the same speed as a lighter frame. This is not a good or bad thing; it is simply identifying the need of the player. If a player with a faster swing uses a racquet that is too light, they will have to slow their swing to contact the ball at the right place, whereas a player with slower swing using a heavier frame would tend to hit the ball late or have to swing harder to make good contact. Also, keep in mind that overall weight is only one factor here. Where the weight is distributed through the length of the frame will be more significant. We will discuss this in more detail in balance and swingweight. Shock (Comfort): This refers to the energy that travels through the racquet and into the player's hand at impact with the ball. Several things can contribute to this, as we will discuss later. If a racquet transmits a lot of shock to a player, he/she may describe the feeling as harsh or firm. If a frame transmits little shock, a player may describe it as soft or comfortable. Shock is what the player feels at the point of impact with the racquet and ball. After the impact occurs, and the ball has left the stringbed, a lingering vibration can be felt and contributes to the sensation the player feels. Spin: This refers to the frame’s ability to enhance spin on the ball. It is important to note that the player’s stroke and swing path dictate whether they will impart spin, how much, and what type, onto the ball. The frame can only enhance the spin, not create it. In other words, if a player has a very flat and level stroke, even a racquet designed to enhance spin won't help them get spin without changing their swing. UNDERSTANDING RACQUET SPECS Manufacturers create racquets with different levels of Power, Maneuverability, Shock and Spin by making racquets with different specifications. Specs are what truly make every racquet unique. To effectively help a player narrow down their choices of frames, you have to understand the specs of the frames and how each spec affects Power, Maneuverability, Shock and Spin. LENGTH: This spec simply refers to the overall length of the racquet from the end of the butt cap to the tip. The standard length is 27 inches or about 686 mm. However, junior racquets tend to be shorter to match the height of the player. Longer racquets became popular several years ago as manufacturing processes allowed the racquets to be made longer and still maneuverable. 29 inches (737 mm) is the maximum legal length under the official rules of tennis. HEADSIZE: This spec refers to the hitting surface or strung area of the racquet. Modern tennis racquets will range in headsize from 85 sq. in. (583 cm2) to 137 sq. in. (820 cm2). The official rules of tennis dictate that the overall width cannot exceed 12 ½ inches or 31.75 centimeters. The hitting surface cannot exceed 15 ½ inches (39.37 cm) in length and 11 ½ inches (29.21 cm) in width. STIFFNESS (FLEX): This refers to how stiff the racquet is, or how difficult it is to bend. This is not something that can be seen or felt by hand as the difference is too minute. There is specialized equipment to measure the flex or stiffness of a frame. A higher reading means the frame is stiffer or more difficult to bend. WEIGHT: This refers to the overall weight of the frame and is simply measured by standing or laying the frame on a scale. Most tennis frames will weigh from about 8 ounces (227 grams) to about 13 ounces (369 grams). There is no rule governing how light or heavy a racquet can be. BALANCE: This refers to the point on the racquet where it will balance lengthwise. It may also be referred to as the center of gravity. This simply shows how the weight is distributed along the length of the frame. When the frame is balanced on a balance board or other device, half the weight is on one side and half on the other side. SWINGWEIGHT: This is probably the most complicated spec to understand, but is also the most important to how the racquet feels and plays in the player's hand. It is a dynamic measurement of how difficult the frame is to swing. It is a combination of the weight and the balance. There is specifically designed Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 4 USRSA Racquet Professional Study Guide – Racquet Technology equipment (swingweight scales) to measure this. The higher the swingweight, the more difficult it is to swing around. STRING PATTERN: This refers to the number of main (vertical) and cross (horizontal) strings in the racquet. While this is the main reference, it can also refer to the spacing of the strings within the pattern or whether the pattern is perpendicular (standard) or some other variation such as a fan or diagonal. OTHER SPECS: There are numerous other specs of frames, but we are going to limit our material to the seven described above. The reason for this is that other specs are minor and are generally used to contribute to one of the specs listed. An example is the material used in the racquet or the beam height of the frame. Both are specs but are used to influence the stiffness of the frame. We will discuss some of these within the parameters of each spec and how it affects play. SPECIFICATION EFFECTS To better understand the effects of each of the specifications, we are going to describe these with the understanding that ALL OTHER THINGS ARE EQUAL. Since each spec has a specific correlation, it is important to understand it in this context. In actuality, it is the combination of the various specs in a frame that provide the uniqueness of each frame. But, to make that correlation, you must understand each specs' contribution. LENGTH: All other things being equal, as the length of the racquet increases, Power will increase due to increased racquet head speed. At a given swing speed, the further the hitting surface is from your hand the faster it will travel. This increase in racquet head speed will also increase Spin. At the same time, the Maneuverability is decreased because more weight is positioned further from your hand. Shock is decreased slightly because there is more racquet material to dampen the shock. HEADSIZE: All other things being equal, as the Headsize increases, so will Power. This is because the strings become longer and create more of a trampoline effect on impact with ball. Maneuverability is slightly decreased due to the larger surface creating more wind resistance. Shock is decreased due to the longer string plane deflecting more and absorbing more at impact. Spin potential is increased because the spacing between the strings is increased allowing the ball to penetrate deeper into the string plane and allowing the strings to bite into the ball better. STIFFNESS (FLEX): Power will increase with a stiffer frame. The stiffer frame flexes less upon impact with the ball; therefore, it absorbs less energy and returns more energy to the ball. For that same reason, the stiffer frame will transmit more shock at impact. A stiffer frame will also slightly increase spin potential due to the ball leaving the racquet with more energy. Stiffness will not affect maneuverability. Until around 1980 manufacturers relied solely on material placement in determining the stiffness of a frame since the beams or frame tubes were all pretty uniform in thickness. Some frames were stiffer in the shoulders, some stiffer at the tip as a result of placing higher modulus graphite or manipulating the fiber orientation in these areas or sometimes adding other materials such as boron or ceramics. In the late 1980's manufacturers introduced the "widebody" frames to the market with various beam heights. This design is still evident today, and manufacturers enjoy the added variable of adjusting beam height or cross-section to make a frame stiffer or more flexible. Material aside, increasing the cross section of a frame during production is the most effective way to increase stiffness. WEIGHT: Power increases as the weight of the racquet increases because there is simply more mass or weight impacting the ball and sending more energy to the ball at impact. Maneuverability will decrease simply because the heavier frame is harder to swing. As the weight increases in the racquet, shock is decreased because the heavier weight of the racquet is less affected by the impact. Think of the collision of the racquet and the ball as a car crash. If a large SUV and a small sports car collide, the heavier SUV will feel less of the impact than the smaller car. Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 5 USRSA Racquet Professional Study Guide – Racquet Technology Although all racquets will outweigh the tennis ball, the more that weight difference, the less shock will be felt. Increasing the weight of the frame is the most effect way to reduce shock. Spin potential will increase slightly because the frame is transmitting more energy to the ball at impact and the glancing blow will impart more spin. While the weight is a key component, the distribution of that weight along the length of the frame has the biggest effect on the feel and play of the frame. BALANCE: This component is a static measurement of that weight distribution and is pretty straightforward although it can be confusing since it is referred to in several ways. Frames can be headlight, headheavy or evenly balanced, which is a general categorization. The balance of a racquet is simply the center of gravity. It is the point where the racquet will balance as demonstrated in Figure 2.1. Figure 2.1 – Balance Board The confusion comes with the various methods used to express this measurement. The most widely accepted method today is the measurement from the end of the butt of the racquet to the balance point. Most often expressed in millimeters or centimeters, but it can also be expressed in inches. This expression is preferred since the length of the frame doesn't matter. You may also see references to distances headlight or headheavy; such as the frame is 1-inch (25 mm) head-light. To use this reference, you will also need to know the overall length of the frame since this reference is from the mid-point of the frame. A 28-inch (710 mm) frame would have a mid-point of 14 inches (355 mm). Another common expression is "points" headheavy or headlight. A "point" is 1/8 of an inch, so the frame that is 1-inch headlight would be expressed as 8 points headlight. A balance board is a common tool to measure the balance. The frame is placed on the device as shown in Figure 2.1 and the bar is rolled back and forth to find the balance point (center of gravity) of the frame. The scale of the device can be read by aligning the butt of the racquet to the measurement at the point that it begins to lift as shown in Figure 2.2. Some devices have "points" scales for standard length frames but other lengths would have to be calculated. Generally, the balance will move 1 cm for a strung racquet versus unstrung as the added weight of the string will shift the balance point approximately 1 cm. Figure 2.2 – Balance Board Scale Beyond the static measurement, balance also contributes to the feel of the racquet in terms of weight. Since the racquet is held by the handle, a 285-gram (10 oz.) racquet with a headlight balance will feel much lighter than a 285-gram (10 ounce) racquet that is headheavy. On the headheavy racquet, the mass is further from the hand and feels heavier, although the actual weight is the same. This feeling can actually be calculated, and is referred to as the Pick-up Weight or First Moment or Static Moment. It can be calculated as the weight of the racquet multiplied by the distance from the balance point to the hand, divided by 100. The higher the value of the first moment, the heavier the racquet will feel as it is held by the handle. Overall length also enters into this since a longer racquet is moving some of the mass further from the hand. A 29-inch (737 mm) racquet, weighing the same as a 27-inch (686 mm) racquet, would need to have a balance point one inch (25 mm) closer to the handle (half the increase in length) to feel the same when held at the handle. Using this formula, a 28-inch racquet weighing the same as a 27-inch (686 mm) racquet would require a balance point 1/2" (13 mm) closer to the handle to feel the same. This is why the USRSA rarely refers to racquets balance in terms of points headheavy or headlight. Rather, the USRSA will generally list the location where a racquet balances in terms of the distance (centimeters or inches) from the butt end. This allows for comparing the balance point of racquets of different lengths without doing any conversions. Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 6 USRSA Racquet Professional Study Guide – Racquet Technology Power will increase as the balance point goes higher, meaning the balance point is further from your hand or more headheavy. This is because there is more mass or weight in the area of the racquet striking the ball, transmitting more energy to the ball. As the balance point goes higher, the maneuverability will decrease. As the weight goes further from your hand it feels heavier and is harder to maneuver. A good analogy is a hammer. If you pick up a hammer by the head, it feels much lighter than when you hold it by the handle and the weight is further away. Shock will decrease as the balance point goes higher because there is more mass driving through the impact of the ball. Spin potential will also increase because there is more mass driving through the impact and the glancing blow of the spin stroke will impart more energy and spin to the ball. SWINGWEIGHT: Swing weight (also referred to as Second Moment or Moment of Inertia) is a dynamic measurement and is probably the most important characteristic in determining the feel and maneuverability of a racquet during play. Racquets with a greater swingweight tend to feel heavier and less maneuverable than a lower swingweight racquet of similar static weight and balance. Two racquets of identical weight and balance can have very different swingweights, and therefore will perform very differently. To illustrate, imagine two poles with two weights attached. If the weights are affixed at opposite ends, the swingweight of the pole is maximized. However, if the weights are closely situated, swingweight is minimized. Two racquets balanced this way will have totally different playing characteristics. Yet they will be identical in weight and balance as shown in Figure 3. The same holds true with racquets of differing lengths. The 10ounce (285 grams), evenly balanced 29-inch (737 mm) racquet discussed earlier, will have a completely different feel in motion than a 10-ounce (285 grams), evenly balanced 27-inch (686 mm) racquet. In order to equalize the swing weight of these two racquets, the balance point of the 29-inch (737 mm) racquet would need to be placed one inch (254 mm) closer to the handle, Figure 3 – Swingweight Difference because the even-balance point is one inch (254 mm) further out than on a 27-inch (686 mm) racquet (14-1/2 inches or 368 mm vs. 13-1/2 inches or 343 mm). Power will increase as the swingweight goes higher. As explained in both weight and balance, a frame with a higher swingweight will have more mass at impact and return more energy to the ball. Maneuverability will decrease as the swingweight increases for the same reasons: More mass and further from your hand. In the most simplistic view, swingweight is a measurement of maneuverability. Shock will also decrease as the swingweight goes higher, as more mass will absorb more of the impact. Spin potential is also increased, as there is more mass at the impact and more energy imparted to the ball. Torsional Stability is resistance to the racquet twisting. This is affected by several factors such as weighting the perimeter of the hoop of the frame either by the manufacturer or a customization by a qualified racquet technician adding weight at 3 and 9 o'clock. Proper handle size and a high friction grip can also increase stability. STRING PATTERN: A denser string pattern will decrease power, and a more open pattern will increase power. The denser the pattern, the stiffer the string bed will be. This has the opposite effect of the frame stiffness. The open pattern (less dense) will deflect more and trampoline the ball off the strings deeper into the court. Because the denser pattern will deflect less on impact, it will propel the ball less. Maneuverability will not really be affected by string pattern enough for a player to feel usually. A denser pattern will weigh ever so slightly more and create more wind resistance on the swing but not enough to feel. Shock will increase with a denser string pattern since the denser string pattern will create a stiffer string bed and less impact will be absorbed. Spin potential will also decrease with a Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 7 USRSA Racquet Professional Study Guide – Racquet Technology denser string pattern since the strings will be closer together and will bite into the ball less at impact. Remember, it is very important that the above explanations are under the assumption that all other things remain the same. For example, we said that a heavier racquet is more powerful, which is true. However, if the racquet is so heavy that the weight slows the players swing speed down significantly it could have the opposite effect. When you are advising customers, it is very important to keep all the facts in mind, otherwise you may recommend one thing that would help, but it actually hurts them in another way. THE RACQUET SELECTOR TOOL The previous sections explained how the different specs of a racquet effect its Power, Maneuverability, Shock and Spin. This is valuable information for putting the player together with the racquet that is best suited for their game and style of play. However, with more than 300 current performance racquets on the market at any given time, it is impossible to memorize the specs of every racquet. In this section we will explore a tool available on the USRSA Website www.RacquetTECH.com) that can help wade through the sea of racquets and narrow down the selection for your customer. Racquet Selector Tool: This tool allows the user to search the USRSA database for racquets using all the various specs. First, the user finds the existing racquet in the database, and then enters the criteria for each spec. The user can choose MORE, LESS or ABOUT THE SAME for the new racquet and then prioritize those choices to produce a list of current racquets based on the criteria provided. To use this tool or to get more details, USRSA members can access it through the TOOLS menu on the website. For more information, feel free to contact the USRSA. OTHER CONSIDERATIONS: If a player thinks a certain racquet looks cool, they will find a way to play with it. However, we do not recommend cosmetics or player endorsements to be an important aspect when trying to narrow down the racquet selection. We recommend using the specs and tools discussed in previous sections, then a player can consider price and cosmetics among the finalists to decide on their final choice. FRAME SELECTION Fitting the Player: You have learned about your client and now can make suggestions for frames that they should consider. Using your knowledge, you should narrow down the selection to a handful of frames that should meet their needs. DEMO, DEMO, DEMO: After the player has narrowed their selection to a few frames, based on the criteria Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 8 USRSA Racquet Professional Study Guide – Racquet Technology discussed, the next step is a test drive. If possible, they should test two or three racquets at a time. If they take more, they won't be able to give each one a fair evaluation. If they take them out one at a time, it is more difficult to compare. They should use the racquet the same way they play to give it a fair evaluation. They should make sure they serve, return serve and hit various strokes. Each racquet should get at least 15 minutes of playtime. Make sure they understand that the demo will be different than their current racquet and will take time to get used to the feel. It may not be strung exactly for them or have the proper grip size, but they should be able to get a feel for its POWER, MANEUVERABIL TY, COMFORT & SPIN POTENTIAL. If you have input or control of the demo racquets at your facility, you should consider the string and upkeep of the demo racquets. Remember these are tools used in making sales. Stringing the demos with inferior string and not keeping the strings fresh is not a cost savings measure. It is a detriment to selling racquets. Ideally, demos should be strung in the middle of the tension range with a string that is most likely going to be suitable for the type of player. In other words, GameImprovement racquets should have a string that is suitable for players seeking that type of frame. Most importantly, make sure the strings and grips are fresh. After the demo, you should discuss their opinion of each racquet to ascertain what worked and what didn't. If racquet A was too powerful and Racquet B was not powerful enough, then you have narrowed down the target to something in between. By analyzing each of the aspects of Power, Maneuverability, Shock and Spin, you can help narrow down the selection with each demo session. It's true, there is a great deal of information to understand and apply when helping a player select a racquet. However, like everything else, as you practice, you will get better and more efficient. Your student or customer will really appreciate the time and effort that you show through the process. They will be impressed by your knowledge and professionalism, and spread the word about your service. Sizing for the Proper Handle Size: Racquets come in sizes ranging from a size O (or 4 inches) up to a size 6 (or 4 ¾ inches). Each size increase represents an increase of 1 /8 of an inch in the circumference of the handle. Most racquets are available in sizes 1 through 5, however some models may offer a size O and others a size 6. Junior racquets will also offer even smaller sizes. There are a couple of ways to measure the hand for the proper grip size. One is to simply measure the distance from the tip of the ring finger down to the lateral crease in the palm of the hand as shown in Figure 4.1. This distance should match the handle size. The best method is to allow the player to hold the racquet as if they were playing and gauge the gap between the palm and the fingers as shown in Figure 3b. Proper grip size should maintain a "one finger gap" as shown. However, the player could go up or down one size as needed. Figure 4.1 Keep in mind, if the player plans to use an overgrip, these usually increase the size of the handle by 1/16 inch, or a half size. A grip that is too large or too small can lead to arm injuries and errors in stroke production, so it is important to fit the client properly. JUNIOR PLAYERS and JUNIOR RACQUETS Figure 4.2 Just as with adults, it is imperative that children play with proper equipment to maximize their enjoyment and reduce the risk of injury. It is important to note that while junior racquets are basically Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 9 USRSA Racquet Professional Study Guide – Racquet Technology scaled down versions of adult frames, the children are not simply scaled down versions of adults. Their bodies are developing and growing, and they are much more susceptible to injuries from repetitive motion and shock load than adults. Using the appropriate racquet and balls is very important to maximize the player's enjoyment and development in the game, as well as reducing the chance of injury. Junior racquets will generally fall into two categories: Beginner and Premium. Beginner Junior Frames: These racquets are usually available in varying lengths from 18 inches (46 cm) to 26 inches (66 cm). They will be sold pre-strung and are relatively inexpensive. Most will be made of aluminum with grip sizes generally correlated to the length of the racquet. The longer the racquet, the larger the grip will be. Variance in grip sizes is not offered. These racquets are good for initiation to the game and developing basic eye-hand coordination. Sizing to the correct length and grip is vital as described below. Once the player has developed more advanced skills and is beginning to play/compete, it is time to move to a premium frame. Premium Junior Frames: These racquets are available in various lengths as small as 22 inches (55.88 cm) but are prevalent at 25 inches (63.5 cm) and longer since the players ready for these frames are generally older and taller. These frames will be made of composite materials such as graphite and are scaled down versions of adult frames. These frames are better constructed and more expensive than beginner frames. They will be more stable for juniors that can hit with some pace and direction but are not yet physically ready for a full-size adult frame. Proper Fitting for the Junior Player Although there are fewer choices of racquets for junior players than there are for adults, it is just as important to properly fit the player in the correct racquet. With adults our concentration is centered on their swing length and speed, but with children, racquet length and the size of the child are the key components. Having a racquet that is too short or too long will not only make the game harder, but could easily lead to injury. While there are varying opinions of how to fit a junior racquet based on factors such as age and height, we feel that height is the correct measure. The length of the racquet should coincide with the player's height. However, there exceptions to every rule, so you may have a child that is shorter in stature but strong and able to handle a longer racquet or a tall child that is weaker and needs to stay with a shorter frame a bit longer. A good way to measure for correct racquet length is to have the player stand up straight with arms relaxed at their side. Place the racquet at their Figure 5.1 side with handle facing up. The player should be able to grasp the butt of the handle without bending or crouching, arm relatively straight, and the racquet should barely touch the ground (Figure 5.1). Remember, this is a good baseline measurement, but you will have to consider each player individually. If the player has been playing for a while and has developed good strokes, they may be able to handle a longer racquet. Ready for an Adult Frame: As soon as a player is tall enough and is hitting balls with pace and control, they should move into an adult frame. Manufacturers offer plenty of transitional frames that have a lighter swing weight and are available in a 4-inch (0) grip size. If the player is tall enough and strong enough, these racquets will offer more stability and shock reduction for harder hitting players. String Set-up for the Junior Racquet: Many junior racquets come pre-strung from the factory. The factory string job may suffice for the beginner but should be restrung just like adult frames. Premium frames that are pre-strung should be strung to meet the needs of the player. Players using junior racquets should avoid stiff strings and higher tensions. The shock of the stiffer stringbed, coupled with the light weight of the racquet, could cause injury to developing bodies. Juniors often play much more frequently than adults and should also be restringing more often. Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 10 USRSA Racquet Professional Study Guide – Racquet Technology STRING SELECTION Selecting the right string is just as important as the frame selection, perhaps even more important. Strings are often the most underrated piece of equipment, but they are the most important. After all, they are the only thing that touches the ball. Unfortunately, it is not uncommon for a player to spend weeks, and even months, researching and selecting a new frame, only to spend a minute to select the string to go in it. A frame will only play as well as the strings in it. If a player has decided on the perfect frame, that can all be ruined by choosing the wrong string. Just as with choosing a frame, it is important to find out as much information as possible about the player in order to give them the best advice on choosing the right string set-up (string and tension) to give them the best performance for their game with their frame. Many of the same questions apply regarding their swing type, frequency and skill level, etc. You will also need to ask if they have experienced any injuries or pain when playing. As with frame selection, it is important to know their desire and/or expectation. Are they looking for more power or less power? More spin? More comfort? More durability? The more information you have, the better you can advise them. Choosing the perfect string is much like choosing the frame. First, you have to understand the characteristics of the string, which is what the player feels when they play with the string. Then you have to consider the specs of the string that make it unique from other strings and how those specs effect and influence the characteristics the players feel. Using this information will allow the player to shrink down the selection from more than 1,000 different strings currently available on the market to maybe 4 or 5 to try. Just like with frames, playing with the string is the only way to settle in on the perfect match, but once the player does, they will probably stay with that string for a long time. Stringbed Characteristics: When most players describe a string, they will refer to its performance in 3 Characteristics: Stringbed Stiffness (Comfort), Spin Potential and Durability. When selecting a string it is important to consider each of these characteristics and choose a string that offers the best combination of these characteristics. Like frames, there is no "one size fits all" string. It all comes down to the individual preference of the player. Some will find the stiffness most important while others will consider durability most important. Overall, it is finding what best suits that player and best meets their needs and expectations. STRING SPECIFICATIONS: Visually there is not much difference in string. They may vary in color and thickness. Some may have a stiffer or softer feel in the coil but there is more than meets the eye. Strings can vary greatly from how the materials are put together (construction) to the materials themselves. This is only multiplied when string is installed into the frame. Marrying the characteristics of the string to those of the frame will produce a unique feel. In other words, a certain string installed in a Player frame may produce an entirely different feel than that same string in a Game Improvement frame. MATERIALS: This refers to the actual materials used in making the strings. Today there are 5 primary materials being used for racquet string: Natural Gut, Nylon, Aramid Fiber, Polyester and Zyex. The material directly affects the durability, stringbed stiffness and even the spin potential. Natural gut is made from beef intestines. This natural material is very labor intensive to make, and because of this, is generally the most expensive string on the market. It is also, generally, the most powerful and most comfortable. It often gets low marks for durability but that depends on how the term durability is used. Generally, Natural Gut will not break any sooner than a similar gauge of a multifilament nylon, however it will generally hold tension and resiliency much longer than any of the man-made material strings. So, if the player is not a frequent string-breaker, it could be considered more durable. Nylon is the most widely used material in tennis string, but it also has the widest variety due to the numerous Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 11 USRSA Racquet Professional Study Guide – Racquet Technology construction types (discussed later). Aramid fiber or (Kevlar) strings were very popular for years for their extreme durability and are still available today from some manufacturers. They are generally used in a Hybrid Setup, pairing the Aramid string for the main strings and nylon string for the crosses. The Aramid has almost no elasticity so pairing it with a more elastic string makes it more comfortable and playable. In recent years their popularity has waned in favor of polyester strings that offer more playability although not quite as much durability. Polyester or Co-Polyester strings have become very popular in recent years among pro players and recreational players as well. Co-Polyester simply means some additive has been included into the mix during production, but the general characteristics are the same. These strings are monofilament and usually have a stiff feel. They can be round or formed into many geometric shapes. Recreational players often choose these strings for durability, as they are difficult to break, however they tend to lose tension and playability much faster than any other type of string. Their best attribute is the ability to "snap back" after impact. This quick snap back imparts more spin onto the ball. This only occurs if the player has sufficient swing speed to deform the stiff strings in the first place. Zyex is a proprietary high-performance thermoplastic polymer fiber used in many industries from wiring to industrial belts and filters. As a racquet string it has great tensile strength, stretch and recovery and holds tension extremely well. The fibers are also touted as very abrasion resistant making it an excellent choice for racquet string. STRING GAUGE: This is used to describe the thickness of a string. In the U.S., the higher the number, the thinner the string. However, internationally it is just the opposite. You will also often see "L" following a gauge number such as 16L. The "L" is for Light, meaning that string is on the thinner U.S. Int'l Diameter end of that particular range. As you can see in the accompanying 13 12 1.65-1.80 mm chart, there are some overlaps. For example, a string measuring 1.27 14 11 1.50-1.65 mm mm could be classified as either a 16 or 16L gauge. It is up to the 15 9.5 1.41-1.49 mm manufacturer to decide how they want to market the string. For this 15L 9 1.33-1.41 mm very reason, the USRSA advises to use the actual diameter 16 8.5 1.26-1.34 mm measurement whenever possible. 16L 8 1.22-1.30 mm To the right are the Tennis Industry Association's gauge 17 7.5 1.16-1.24 mm standardization specifications. The string gauge is usually measured 18 7 1.06-1.16 mm under tension. For example, a string that measures 1.26 mm 19 4 0.90-1.06 mm unstrung would appear to be either 16 or 16L. When strung, 20 3.5 0.80-0.90 mm however, the diameter might become 1.21, which would make it a 21 3 0.70-0.80 mm 17-gauge string. 22 2.5 0.60-0.70 mm CONSTRUCTION: The construction of a string refers to how the string is actually put together. There are far too many variations to be covered here. We will cover several of the more prominently used variations on the market and you can see visual cross-sections of these in the accompanying diagrams. As you can see, they run the gamut from a monofilament to a multifilament with many variations in between. Natural Gut - Made from beef intestines, this string sets the standard for optimal playability. Due the labor-intensive manufacturer process, natural gut strings are generally the most expensive. They have a reputation for being delicate but modern technology has greatly improved the durability of natural gut without sacrificing its playing characteristics. Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. Figure 6.1 Natural Gut 12 USRSA Racquet Professional Study Guide – Racquet Technology Monofilament - This is simply one large extruded piece of material to form the string. Many different materials could be used but the most prevalent is Polyester and polyester blends (Co-Polyester). Solid Core/Single Wrap - These popular synthetics derive durability and tension retention properties from a large solid center core. An outer wrap of smaller filaments or fibers assists in retaining Figure 6.2 - Monofilament tension and also protects the core from nicks and abrasions. The number and construction of wrapped filaments, diameters and synthetic blends varies from string to string. Figure 6.3 - Solid Core/Single Solid Core/Multi-Wrap - Similar to the single-core/single wrap, but generally, the center core is smaller in order to accommodate more outer wraps. These outer wraps may be of different materials, different diameters or both. These strings tend to be a bit softer feeling due to the thinner core. Multifilament - This is a coreless string in which multiple synthetic Figure 6.4 - Solid Core/Multi Wrap fibers are twisted in a manner similar to that of natural gut. Fibers can vary in material, thickness and number - from only a few to thousands of micro-fibers. The initial advantage is in playability, although the strings may tend to lose tension more quickly than a string with a center core. However, this "soft" string can compensate for the stiffness felt with many of the modern frames. Advances in high-tech resin bonding agents and coatings have greatly improved this category of strings. Figure 6.5 - Multifilament Multicore/Single Wrap -Advances in construction have made these popular. The multifilament core offers a softer feel, while the outer wraps add durability. Figure 6.6 – Multi Core/Single Wrap Multicore/Multiwrap Advances in manufacturing processes have enabled various different configurations to meet the needs of various player types. Textured - These strings have a Figure 6.7 – Multi Core/Multi Wrap rough texture or feel. This can be accomplished through varying the thickness of the outermost wraps on the string or manufacturing grooves or lines into a monofilament. These are generally marketed as helping to produce spin, although recent research has shown that the string surface has little effect on spin. Figure 6.8 - Textured Composites - This construction can take on several variations. Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 13 USRSA Racquet Professional Study Guide – Racquet Technology Composite strings combine different materials such as nylon and Zyex into one string utilizing the best attributes of the different materials. Figure 6.10 - Geometric or Shaped Geometrics - Shaped strings come in many configurations - flat, square, octagonal, pentagonal, gear shaped and countless more. These are also marketed as enhancing spin. The verdict is not Figure 6.9 - Composite conclusive on whether the shape of the string offer the performance benefits claimed. However, they remain extremely popular and many players feel they are beneficial in enhancing spin. TENSION: This refers to the tension the stringing machine is set to and pulls during the string installation process, or more accurately, REFERENCE tension. Most frames have a recommended tension range set by the manufacturer as the range for optimal performance for that frame. Stringing a frame above the manufacturers recommended range would void the warranty and could damage or ruin the frame. When a player switches to a new frame, it is a good idea to start in the middle of the recommended range to get a feel for the frame, then they can go up or down in tension on the next string job to meet their needs. It should be noted that reference tension is different from actual or dynamic tension. As explained, reference tension is the tension applied during the installation process. Actual tension is the resulting tension after installation and is difficult to measure. Actual tension is usually lower than the reference tension since other factors such as friction, elongation and the string's tension retention capabilities affect the results. If measured, you would probably find that each string would measure at a different tension since there will be many variables such as string length, friction, angle of pull, etc. Also, the cross strings, even though they are installed at the same tension, will have lower actual tension than the mains. This occurs because the mains have less friction during their installation, where cross strings are woven through the mains creating a lot of resistance and friction during the installation. This only means that the resulting stringbed tension is a sum of all the parts and should be measured that way. A more accurate reflection on the actual or dynamic tension is to measure the stringbed as a whole unit. The common way of checking actual tension is to test the entire string bed surface with a device using deflection or harmonics. STRING SPECIFICATIONS EFFECTS It is important to understand what the different specs of string are and how they make each string unique. However, it is even more important to understand how each of these specs effects what the player feels when using a string. In this section, we will discuss how materials, gauge, construction, and tension effect stringbed stiffness, spin potential, and durability. As we have discussed, many factors contribute to how a string will feel and play, but it is important to understand each spec and how their effect can combine with others to choose the right string. As with the frames, we discuss these with the assumption that all other things are the same. Material: The material does affect the feel of the string with Natural gut being the softest and Aramid fibers being the stiffest. Usually, the reverse is true for durability. Beyond that it is hard to gauge the stiffness of a string on materials alone. With today's vast array of materials and construction techniques, the only way to get a true reading of the string's stiffness is to see the USRSA lab rating of stiffness for a particular string. Softer strings are generally going to stretch more on impact and absorb more shock. This results in more energy returning to the ball and propelling it deeper, or in other words, more powerful. Stiffer strings will deform less, and the ball will trampoline less off the strings making the ball easier to control. This is the first consideration for a player of compromising to find the right material. Perhaps giving up a bit of comfort or power to gain more durability or vice versa. Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 14 USRSA Racquet Professional Study Guide – Racquet Technology Gauge: Research shows that there is no direct correlation between gauge and stringbed stiffness. In some strings, the thinner gauge tends to string up stiffer, while in others, the thicker gauge tends to string up stiffer. However, gauge does have a big influence on spin potential and durability. Thinner strings will generally increase spin potential because they are better able to bite into the ball on impact. Thinner gauges are also less durable. Strings generally break because cross strings saw into (and through) main strings. Thinner gauge strings require less sawing to cut through. Construction: The construction of a string will affect all of the characteristics of the string when a player is playing with that string. Generally, strings with more fibers will feel softer and return more energy to the ball than strings with fewer fibers. Strings with more fibers tend to be less durable since those fibers require resin-bonding agents to hold together. These resins take up room meaning there is less material. Geometric or textured string may enhance spin but can also be less durable if their texture or shape cuts or saws into itself more. Tension: It is fairly obvious that as tension is increased, stringbed stiffness will increase. However, the effect of tension on the other two characteristics is not as clear. These questions are the topic of many debates in the tennis industry. Some believe that tighter strings will create more spin; while others believe that looser strings will create more spin. The fact that everyone has not been able to agree suggests, that the answer is not so simple. The question of how tension affects durability is also a complicated one. Some believe that looser strings will tend to move more and, as a result, saw into each other more quickly, while others believe that tighter strings move a little less, but experience more friction when they move, which saws through the strings more quickly. Since these two issues are so controversial, we recommend you use the other specs to effect spin potential and durability. Elongation, elasticity and tensile strength are things you may see or hear in discussion of strings, so you should at least be familiar with the terms and what they mean. Elongation: is a measurement of how much a string will stretch under a given tension. If you tension a 10-inch (254 mm) string at 60 pounds (27.2 kg) and it stretches 1 inch (25.4 mm) then it is said to have an elongation of 10%. If you are comparing the elongation of two or more strings, it is important that all other things be equal. That is, they should be the same length and pulled at the same tension. Elongation is a good measure of the power potential of a string (all other things being equal). The higher the elongation the more power the string will create. Elasticity: is simply the ability of the string to stretch and return to its original shape and condition after ball contact. Tensile strength: is a simple measurement of how much force is needed to break the string pulling it by the ends. While this may reveal how a string will hold up to certain reference tensions, it really does little else to predict the durability of a string in a racquet. The Synthetic Gut MYTH: The term SYNTHETIC GUT is still widely used in the marketplace and creates a lot of confusion among players. Is it SYNTHETIC? Is it GUT? Is it BOTH? The reality is that it is simply a marketing term and has no real definition. Many of the strings on the market labeled "synthetic gut" are simply solid core/multiwrap nylon strings. So, don't be fooled by the name. While they may be good strings, there is really no such thing as synthetic gut - you have either a synthetic string or a (natural) gut string. CONCEPT OF POWER By now you are probably wondering why we haven't talked about how the different specs of a string affect power. We've been saving it for last because it is such a complicated and misunderstood concept that it deserves a section to itself. Copyright © 2020 USRSA. All Rights Reserved. Entire contents and selection, arrangement and presentation of data are fully protected by copyright and may not be reproduced. 15 USRSA Racquet Professional Study Guide – Racquet Technology Research suggests that power may not change with the specs, but rather with the stringbed stiffness only because of trajectory of shots. Keep reading for a better explanation. First, we have to agree on a definition of power. Then we will discuss depth of shots, stringbed stiffness, and selecting the right tension for a player. Looser or Tighter?: For years, people in the tennis industry have been saying string looser for more power and tighter fo